If you think that the risk of extinction in any year is a constant γ, then the risk of extinction by year t is γt, so that makes it the only principled discount rate. If you think the risk of extinction is time-varying, then you should do something else. I imagine that a hyperbolic discount rate or something else would be fine, but I don’t think it would change the results very much (you would just have another small number as the break-even discount rate).
I think there’s a non-negligible chance we survive until the heat death of the sun or whatever, maybe even after, which is not well-modelled by any of this.
If you think that the risk of extinction in any year is a constant γ, then the risk of extinction by year t is γt, so that makes it the only principled discount rate. If you think the risk of extinction is time-varying, then you should do something else. I imagine that a hyperbolic discount rate or something else would be fine, but I don’t think it would change the results very much (you would just have another small number as the break-even discount rate).
I think there’s a non-negligible chance we survive until the heat death of the sun or whatever, maybe even after, which is not well-modelled by any of this.